Abrasive disk



A. J. DOERMANN ABRASIVE DISK March 10. 19 25 File d Jan. 18, 1922Patented Mar. 10, 1925.

LALBERT J'QDOEBMANN, OF CHICAGO, ILLINOIS.

ABRASIVE DISK,

Application filed January 18, 1922. Serial No. 530,}72.

To all whom it may concern:

Be it known that I, ALBERT J. DonR uANN, a citizen of the United States,residing at 1839 West Garfield Boulevard, Chicago, n the county of Cookand State of Illinols, have invented a new and useful Improvement inAbrasive Disks, of which the following is a specification.

' This invention relates to improvements n grinding disks, and moreparticularly 1n disks which are mounted upon fabric backs, the faces ofthe disks being used in the grinding operation. It will be fullyunderstood from the following description, 1llu strated by theaccompanying drawings, in which F i re 1 is a side elevation of a diskprepare in accordance with the present invention, shown face down;

Fig. 2 is a face view of the disk, broken away to show the constructionof the disk, and

Fig. 3 is an enlarged detail view, showing in diagrammatic form thecharacter of the material forming the face of the disk.

. In accordance with the present invent on the abrasive body of thegrinding d sk, which, in the case of a fabric-backed disk, forms theface of the disk, is formed ofparticles of abrasive material and abinder. The binder preferably employed is a magnesium o chlorid cement,into which is incorporate a finely divided corrodible material, such asfinely powdered cast iron. The addition of this material materiallylengthens the grinding life of the disk and permits of the use of aharder binder or cement than would be otherwise possible. It

is readily apparent that other binders may-case,

be employed than magnesium oxychlorid cements: for example, oxyphosphatecements. The abrasive material may be any suitable material, for,example carborundum, alloxite, alumdum or the like, the particles ofabrasive material being hereinafter designated grit.

In forming the fabric-backed disk, the abrasive disk may be formed andsubsequently secured to the fabric back, for example, by means of caseinglue, formaldehyde treated glue, sodium silicate solution or the like.In some cases, the facing of abrasive material may be directly formedupon the fabric back, this being particularly a'dvantageous when thebinder for the abrapreviously been inserted.

chlorid solution may suitably be from 24 sive is of magnesium oxychloridcement.

The drawin gs illustrate a disk made upv of a face or disk of abrasivematerial 5 se cured. by an intermediate layer 6 of glue or sodiumsilicate to a fabric back 7. The abrasive facing ma in the core bemolded on an oiled paper b or press and stripped therefrom to be securedto the fabr1c back. In making up the abrasive face, the grit may bebonded with magnesium oxychlorid cement containing powdered cast iron,the corrosion of which is effected by the chlorid material of thecement. For example,to 16 parts grit and 4 to 5.5 parts of. calcinedmagnesite 0.3 to 1 part of powdered cast iron may be added and themixture thoroughly kneaded with suflicient magnesium chloride solutionto make it damp and pasty. It is then stamped down into a mold, in whichan oiled paper back or a fabric back may have The magnesium to 34 B.(saturated). The saturated solution is preferred, as it causes theformation of a harder and stronger bond.

In preparing .the abrasive body of the disk the cutting" grits arechosen for the particular purpose'in view, as is well known in the art.Thus, for rapid work on large malleable castings, 16 mesh grit may beused for the cutting grit. In accordance with the present' invention,the cutting grits are reinforced with finer grit u .to for example, inthe above case, rom 10 to 20% of finer grit, say 24 mesh, may be addedto make up the grit mixture for ack in a suitable form the abrasive bodyof the disk. In another in which'the cutting grits were made up of 16and 24 mesh grits in about equal proportions, from 5 to 25% of 30 meshgrit was added. In Fig. 3 the reinforcement of the cutting gritwithfiner grit is indicated in an exaggerated manner, the bond beingindicated in black. I,

The oiled paper back may be removed from the abrasive disk body afterits formation; the abrasive body being subsequently secured to a fabricback by'asuitable adhesive, as hereinbefore set forth. If desired, theabrasive disk body formed directly upon the fabric back by placing thefabric back in the mold, coating its surface with a mixture of magnesitewith suflicient magnesium chloride solution may be 1 therefor, the honto permit of a plication with a brush, and forming the a rasive body onthe coated back I claim: t 1. In an abrasive disk body, abrasive gritand a cementitious bond therefor, the

0nd containing finely divided iron.

2. In an abrasive disk body, abrasive grit and a ma esium oxychloridbond d containing finely divided iron.

3. In an abrasive disk body, abrasive grit, the grit comprising cuttinggrit and s 5 to 25% of finergrit, and a cementitious bond containingfrom 0.3 to 1 part of finely divided iron to 16 parts of grit.

4. an abrasive disk body, abrasive grit, magnesium oxycblorid bondformed with saturated magnesium chlorid solution,

and finely divided corrodible material ii corporated in said bond. p

5. In a face-grindin disk, a body coinprising a binder and a rasive gritincorporated therein, the cutting grit being reinforced by upon whichsaid body is mounted.

6. In aface-grinding disk, a body comprising a binder, cutting gritincorporated therein, and finer grit incorporated in the finer grits,and a fabric back

